Governor



Oct. 18, 1949. w. H. HARSTICK GOVERNOR Filed. Nov. 7, 1945 Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE GOVERNOR William H. Harstick, Richmond, Ind., assignor to International Harvester Company, a corporation of New Jersey 4 Claims.

This invention relates to a speed governor and particularly to a speed control means for power driven devices such as cream separators or the like.

More specifically the invention concerns a novel mechanism for controlling the speed of a series wound electric motor.

It is one of the characteristics of a series wound electric motor to operate at a constantly increasing speed until the windage or load balances the motor torque. It is apparent therefore that in order to maintain the motor at a certain desired speed, the load applied would have to be constant. Whenever the load, therefore, decreases, the motor in turn will speed up causing undesirable results in operations where a constant speed is necessary. This is especially true in the application of cream separators where the quantity of milk going through the bowl is subject to change at the beginning and ending of the separating operation, and speed control over the rotation of the separating bowl is necessary. Variations in the speed of the motor may also be due to line voltage variations, temperature changes or excessive wear of the working parts of the motor. Any one of these may cause an inconsistent speed that will be detrimental to the operation performed.

Therefore, an object of the present invention is to provide an improved mechanism for controlling the speed of a series wound electric motor.

Another object is to provide an improved speed control mechanism for a series wound electric motor using air resistance as a, loading and speed limiting medium.

A further object is to provide a speed governing means for a motor, the effectiveness of which can be controlled by a change in the air pressure within the governing means.

Other objects and advantages will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawings, wherein:

Figure 1 is a view in side elevation of a cream separator with a sectional showing of the power drive and governing means therefor;

Figure 2 is an enlarged sectional view of the governing mechanism; and

Figure 3 is a sectional view taken along the line 3-3 of Figure 2, showinga portion of the governing mechanism.

Referring to the drawings, the numeral [0 designates a cream separator. The cream separator 10 is carried on a supporting structure II and includes a cover l2 having discharge spouts and M. A supply can l5 has a faucet l 6 through which whole milk is discharged into a well, not shown, in the cover l2. A separating bowl I! is positioned within the cover l2 and includes a plurality of separating disks l8.

An electric motor is generally designated by the numeral [9, said motor comprising a housing 20, an armature 2| rotatably mounted on a vertical drive shaft 22, field poles 23' and 24, and a series wound coil 25. I

The uppermost portion of the vertical shaft 22 is journaled in a bearing member 26 supported in the housing 23, said shaft extending upwardly into the separating bowl ll for rotatably supporting same. A cooling fan 2'! is positioned on the vertical shaft 22 between the bearing member 26 and the armature 2|.

The lowermost portion of the vertical shaft 22 is journaled in a bearing member 28 centrally carried in the top wa1l 23 of a governor housing 33. In addition, said housing 30 consists of a side wall 3| and a bottom wall 32 having a centrally located air inlet opening 33, in axial alinement with the vertical shaft 22. The housing is so constructed that there is a minimum of clearance between the outer edges of the impeller and the inner walls of the housing.

The bottom wall 32 is shaped to provide an annular channel or passage 34 at the periphery of the housing 30. This channel or passage is formed by a portion 35, of the wall 32, extending upwardly and outwardly from the housing 30 and terminating in a horizontal surface 36. A plurality of slotted discharge openings 31 are formed in the surface 36 and communicate with the channel 34. A relief valve ring 33, annular in shape, extends around the outer periphery of the house ing 30 and is seated upon the horizontal surface 36 thereby covering and sealing the discharge openings 31.

An impeller 39, consisting of a plurality of impeller plates or vanes 40, is positioned Within the housing 30, and is connected to the vertical shaft 22 for rotation therewith. The motor l9 and the governor housing 39 are suitably shock mounted by a plurality of supporting cushion members M and 42.

During the operation of the cream separator, as the maximum quantity of milk is fed to the separating bowl, the electric motor will run at a certain desired speed. During this time the impeller will rotate within the housing but will not build up a sufficient pressure therein to unseat the relief valve from the air discharge openings. The

I3 55 impeller is being rotated within the housing and the air therein is also being rotated by the impeller vanes. The only restraining medium on the impeller at this stage would be the resulting surface friction of the air on the walls of the housing. Since a minimum amount of clearance is provided between the outer edges of the impeller and the inner Walls of the housing, most of the mass of air is rotating at the same speed as the impeller with a minimum of air turbulence. Thus there is little work done by the impeller at this point, and it is not effective as a governing device. As the quantity of milk fed to the separating bowl decreases or as other variables cause the motor to speed up, the impeller will rotate at a speed sufficiently high for the air pressure within the housing to unseat the relief valve from the discharge openings. The flow of air through the inlet opening and the expulsion thereof by the ends of the impeller will be a sufficient load on the motor to compensate for a decrease in the flow 'of milk fed to the separating means. When the pressure within the housing is sufficient to unseat the valve'the mass of air which has been rotating with the impeller is forced outwardly through the discharge opening. The air which then enters tlnfough the air inlet opening must be brought up to the speed of the impeller. Bringing'thismass of air up to'the speed of the impeller andthe resultant consumption of energy provides theload on the impeller which results in the governing action of the'motor. The governor therefore is responsive to the smallest variation which might occur in the speed of rotation of the motor. Thus the motor can be operated at the same desired speed as when a full milk flow is effected and inherent speed variations of the motor will be controlled. The amount of air pressure necessary to unseat the relief valve can be regulated by changing the weight of the valve ring.

A full disclosure of the operation of the invention is apparent from the foregoing description. It is tobe understood, however, that modifications can be made that do not depart from the spirit of the invention as indicated .by the scope of the appended claims.

What is claimed is:

l. A cream separator having ahigh speed separating bowl and a high speed series wound .electric motor coupled thereto for driving same, in combination, a governor comprising an impeller connected to the motor for rotation therewith, a'housingassociated with the impeller, said housing being provided with a wall having an air inlet opening positioned near the center of rotation of said impeller, a circumferentially extending channel formedin the housing adjacent the peripheral edges of said impeller, said channel having a discharge opening, and valve means carried by the channel and substantially sealing the discharge opening, said valve means being adapted to be displaced away from said opening upon a predetermined build-up of air pressure provided by the rotation of the impeller'within the housing.

2. A cream separator having a high speed separating bowl and a high speed series wound electric motor coupled thereto for driving same, in combination, a shaft rotatable with said motor, an impeller connected to the shaft for rotation therewith, a housing associated with the impeller, said housing being provided with a wall having an air inlet opening, a circumferentially extending channel at the peripheral portion of said housing, said channel being formed with a vertically extending portion terminating in a horizontal surface, said surface having a plurality of discharge openings therein, and an annular valve means seated on said channel for sealing the discharge openings, whereby when suflicient air pressure is built up within the housing by the high speed rotation of the impeller said valve means "is displaced to permit discharge of air through the discharge openings.

3. A cream separator having a high speed separating bowl and a high speed series wound electric motor coupled thereto for driving same, in combination, a-shaft extending from the motor and being rotatable therewith, an impeller connected to 'said shaft, :a housing surrounding the impeller, said housing being provided with a wall at its lower extremity, said wall being formed with a centrally located air inlet opening in alinement with :said :shaft, an annular channel formed around said housing at the periphery of the impeller,.said channelbeing formed with a vertically extending portion terminating in a horizontal plane and providing a surface annular in shape, a discharge opening iformed in said channel and terminating in said surfacema valve ring seated on'said surface for sealing the discharge opening :by the 'force of its own weight, whereby when sufficient air pressure is built -up within the housing by the high speed rotation of .the impeller, said valve ring .isdisplaced to permit the discharge of air through the discharge opening.

4. A cream separator having/a:high-speed.sepa ratingbowl and a high-speed series wound electricmotor connected thereto for driving the same, in combination, a governor comprising an impeller-connected to the motor for rotation therewith, a housing having an inner peripheral wall enclosing and concentric with said impeller, the peripheral edges of said impeller being slightly spaced from'the innerperipheral wall of the housing, an .air inlet :insaid housing, .said air inlet being positioned .substantially near the axis of rotation of saidimpeller, an air discharge opening formed in saidihousing substantially close to and adiacent the peripheral edges of the impeller, and valve means constructed and arranged to normally seal the discharge opening during relative low-speed rotation of the electric motor, said valve means being displaceable from the discharge opening bythe air pressure within the housing during relative high-speed'rotation of the motor, whereby air continually enters into said housing and is directed outwardly through the discharge opening thereby placing a loa'd on'said motor and retarding the speed of the same.

WILLIAM H. .HARSTICK.

REFERENCES CIT-ED The following references are of record in the file of this patent:

UNITED STATES I PATENTS Number Name Date 1,483,075 Chilton Feb. 12, 192.4 2,162,541 Walker June 13, 1939 2,425,178 Ellerbeck Aug. '5, 1947 FOREIGN PATENTS Number Country 'Date 311,502 Great Britain May 16, 1929 

